1. Field of the Invention
The invention relates to a coal-cutting machine having an all-round swivelling jib boom, on which cutting implements are rotatably supported, and a loading means comprising a loading platform which can swivel about an axis extending transversely to the longitudinal direction of the machine.
2. Description of the Prior Art
In conventional coal-cutting machines of the kind mentioned at the outset, the loading platform can be swivelled independently of the pivoting position of the cutting arm or jib boom, the swivelling capacity of the loading platform being restricted to a swivelling of the loading platform about a substantially horizontal axis, and the cutting arm or jib boom being connected to a swing gear which permits a swivelling about an essentially horizontal axis and a pivoting about a substantially vertical axis. Swing gear of this kind must withstand the relatively large forces of reaction during hewing or cutting of rock and must therefore, as a rule, be of relatively large dimensions. In order to reduce the overall dimensions, in particular the height, of a coal-cutting machine, it has already been proposed in this context that the swing gear for the swivelling of the jib boom in the horizontal direction be designed to be separate from the swing gear for the pivoting of the cutting arm in the vertical direction. There is, however, particularly in the case of low-head machines, the danger of a collision between the loading platform and the cutting arm, when swivelling the loading platform with simultaneous pivoting of the cutting arm. A series of arrangements has, therefore, already been proposed, which arrangements are intended to define the swivelling angle of the loading platform and of the cutting arm relative to each other or, otherwise, to stop the swivel drives when an unsafe proximity is reached between loading platform and cutting arm.